pre-commit is a pre-commit hook installer for git. It will ensure that your npm test (or other specified scripts) passes before you can commit your changes. This all conveniently configured in your package.json.

But don't worry, you can still force a commit by telling git to skip the pre-commit hooks by simply committing using --no-verify.

It's advised to install the pre-commit module as a devDependencies in your package.json as you only need this for development purposes. To install the module simply run:

npm install --save-dev pre-commit

To install it as devDependency. When this module is installed it will override the existing pre-commit file in your .git/hooks folder. Existing pre-commit hooks will be backed up as pre-commit.old in the same repository.

pre-commit will try to run your npm test command in the root of the git repository by default unless it's the default value that is set by the npm init script.

But pre-commit is not limited to just running your npm test's during the commit hook. It's also capable of running every other script that you've specified in your package.json "scripts" field. So before people commit you could ensure that:

• You have 100% coverage
• All styling passes.
• JSHint passes.
• Contribution licenses signed etc.

The only thing you need to do is add a pre-commit array to your package.json that specifies which scripts you want to have ran and in which order:

{
  "name": "437464d0899504fb6b7b",
  "version": "0.0.0",
  "description": "ERROR: No README.md file found!",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: I SHOULD FAIL LOLOLOLOLOL \" && exit 1",
    "foo": "echo \"fooo\" && exit 0",
    "bar": "echo \"bar\" && exit 0"
  },
  "pre-commit": [
    "foo",
    "bar",
    "test"
  ]
}

In the example above, it will first run: npm run foo then npm run bar and finally npm run test which will make the commit fail as it returns the error code 1. If you prefer strings over arrays or precommit without a middle dash, that also works:

{
  "precommit": "foo, bar, test"
  "pre-commit": "foo, bar, test"
  "pre-commit": ["foo", "bar", "test"]
  "precommit": ["foo", "bar", "test"],
  "precommit": {
    "run": "foo, bar, test",
  },
  "pre-commit": {
    "run": ["foo", "bar", "test"],
  },
  "precommit": {
    "run": ["foo", "bar", "test"],
  },
  "pre-commit": {
    "run": "foo, bar, test",
  }
}

The examples above are all the same. In addition to configuring which scripts should be ran you can also configure the following options:

• silent Don't output the prefixed pre-commit: messages when things fail or when we have nothing to run. Should be a boolean.
• colors Don't output colors when we write messages. Should be a boolean.
• template Path to a file who's content should be used as template for the git commit body.

These options can either be added in the pre-commit/precommit object as keys or as "pre-commit.{key} key properties in the package.json:

{
  "precommit.silent": true,
  "pre-commit": {
    "silent": true
  }
}

It's all the same. Different styles so use what matches your project. To learn more about the scripts, please read the official npm documentation:

https://docs.npmjs.com/misc/scripts

And to learn more about git hooks read:

http://githooks.com

MIT